Metal Matrix Composite Specimens Research Articles

Casting of nickel powder based MMC using microwave energy

In this paper, an experimental setup is developed to cast a metal matrix composite (MMC) specimen, by using microwave energy as a heat source. A MMC (Nickel and 15 % of SiC by weight percentage) specimen of size 140 × 30 × 2 mm3 is in-situ cast by using a domestic microwave applicator at 2.45 GHz frequency, and 900 W, power output. As per selected process parameters, the exposure time to cast MMC specimen, inside an electromagnetic environment is optimized as 33 min. A COMSOL Multiphysics software tool is also used to model the in-situ microwave-assisted casting setup. Numerical simulations are performed to visualize the microwave heating effects within the applicator cavity. Microwave heating effects are analyzed in terms of electric field distribution, resistive heating and temperature profile. As per the simulation study results, maximum electric field intensity (4.46 × 104 (V/m)) is observed around the mold. Resistive heating losses are maximum (4 .9× 109 W/m3) in the susceptor zone. It is observed from the simulation study, that uniform heating of the specimen is observed throughout the cross-section and the melting temperature of the specimen is achieved in 38 min. A good correlation is observed between experimental and simulation study results in terms of exposure time of cast specimen and microwave heating effects within the applicator cavity

Investigation of corrosion behavior of boron carbide reinforced AA7075 powder composites

This study was carried out in order to provide an example for the composite materials produced using powder metallurgy, which is frequently employed in the automotive and aerospace fields. In this study, powder metal matrix composite specimens were produced by using unreinforced AA7075 alloy, 10%B4C reinforced AA7075 alloy and 20% B4C reinforced AA7075 alloy with powder metallurgy method. The density of AA7075 is 2.78, the density of %10 B4C + AA7075 is 2.67, the density of %20 B4C + AA7075 is 2.62 g/cm3. The hardness value of the unreinforced AA7075 samples was 45.56 before the heat treatment and 63.2 after the heat treatment; the hardness value of the 10% B4C reinforced AA7075 sample was 79.42 before the heat treatment and 87.24 after the heat treatment; and the hardness value of the 20% B4C reinforced AA7075 sample was 95.34 before the heat treatment and 102 after the heat treatment. Corrosion resistance of composites was investigated with potentiodynamic polarization. As a result of the corrosion test, the best corrosion resistance was measured in the 20% B4C reinforced AA7075 sample, and the lowest corrosion resistance was measured in the unreinforced AA7075 sample.

Investigations on mechanical behavior of processed MMCs of Al6082 and reinforcement particles B4C by powder metallurgy technique

In this current research, Al6082 is a base material which is incorporated into the boron carbide (B4C) strengthens particle. The metal matrix composites (MMCs) of Al6082 and B4C were produced by the powder metallurgy (PM) technique. Those chosen fractions of B4C with weight ratio are 0, 3, 6, and 9 % and these mixed powders are initially treated with ball milling and compaction for cold process with maintaining parameters are 80 bar and 9.81 kN. Then sintering process was approached with theses MMCs specimens to produce the magnesium boron carbide composites. During the process, sintering temperature was maintained at 1200 °C in the tubular furnace. The following characteristics compressive, hardness and impact properties were investigated on the magnesium boron carbide composites samples. From the results, the increasing of boron carbide at 9 % wt. attained superior mechanical properties. Finally, the un-reinforced magnesium alloy was attained lesser mechanical characteristics when compared to the boron reinforced magnesium composites. The well blended between the boron carbide and magnesium alloy creates intermetallic bonding efficiently and homogeneous dispersion was generated.

Multi-criteria decision model for selection of a material suitable to lightning strike protection in aerospace applications

In order to protect the aerospace structures against electromagneticinterference (EMI) caused by lightning strikes, metallic meshes or foils are currently being used. But the additional weight of metallic meshes cause counterbalance of weight saving imparted by the composite materials. In this context, Al6061 hybrid metal matrix composite specimens with different proportions of SiC, Al2O3 and fly ash particulates as reinforcement materials have been prepared and tested their characteristics suitability to lightning strike protection (LSP). As there is a conflicting nature among these properties a multi-criteria decision model using AHP, Entropy and TOPSIS techniques with a view to select appropriate specimen to meet the objective. The results of the proposed decision model are compared with that of the other methods VIKOR and PROMETHEE so as to validate the results. The same weightages for the properties are used in all the three methods. The proposed decision model is the robust one for ranking of the materials.

Fabrication and Tribological Behavior of Al3003-SiC Reinforced MMCs

The world is moving in the direction of development of novel materials, there must be an alternative for everything which makes utilization of resources efficiently. In this domain, the significance of Aluminium (Al) Metal Matrix Composites (MMCs)use increased in many industrial segments.This paper mainly focuses on the tribological behavior of Al3003 alloy with is reinforced with Silicon Carbide (SiC) powderof 25μm size. The Al3003-SiCMMCs were fabricated by using liquid metallurgy technique stir casting process. The SiC reinforcements were incorporated 0 to 4.5% in the phases of 1.5% weight percent (wt%). The obtained MMC specimens were subjected to investigative studies related to density, optical andtribological properties. All the studies and experimental work were carried out in accordance to the ASTM standards. The Al3003-SiC composites theoretical and practical evaluated density values are in line with each other and increased with increase in SiC amount in Al3003 matrix material. The optical micrographs of the Al3003-SiC MMCs showed respectable bonding between matrix and reinforcement particle with minimal casting defects. The sliding wear tests have been done on Pin on Disc tribology meter at different loads varying 10 to 40N in the strides of 10Nby maintaining other tribological parameters constant. The wear test outcomes showed that higher resistance to wear was shown by Al3003-SiC composites compared to unreinforced alloy and the composite contain higher SiC amount showed highest resistance to wear.

Effect of dry sliding wear parameters on the tribological behavior of aluminum hybrid metal matrix composites

Abstract The influence of different weight percentages of Tungsten Carbide (WC) and Graphite (Gr) in an Aluminium LM6 Alloy (Al-Si12) was investigated for the Tribological aspects. Aluminium is known to possess poor tribological characteristics – this research work primarily focuses on how it’s possible to enhance the tribological characteristics of aluminium by incorporating the reinforcements Tungsten Carbide and Graphite. Tungsten Carbide is an extremely hard compound with a Vickers hardness number of about 2600. On the other hand, Graphite and graphite powder, which are highly refractory, are valued in industrial applications for their self-lubricating and dry lubricating properties. We performed standardized tests on the aluminium hybrid metal matrix composite specimens and determined the exact weight percentage of reinforcement for optimum wear properties as well as for tensile strength. The Pin-on-Disc sliding wear test was performed under the action of different contact loads following the ASTM G99 Standard. We then performed statistical analysis by Taguchi’s Technique and Analysis of Variance (ANOVA) to determine the most dominating factor that influences Wear Rate for the optimum weight percentage of reinforcement. By enhancing wear resistance of Aluminium, the material can be used in applications where low weight, high strength and corrosion resistance are key factors in addition to high wear resistance.

Experimental investigations of material removal rate on Mg/SiCp-flyash hybrid metal matrix composites by electrical discharge machining

The widening growth of the mechanical industries largely associated with enormous requirement of composite materials due to their light weight and enhanced mechanical properties. Electrical Discharge Machining (EDM) is an imperative modernistic machining technology employed for cutting difficult-to-machine and new age-band of materials. In this research work, Mg/SiCP-Fly-ash hybrid metal matrix composites (MMCs) was fabricated by powder metallurgical route and machined by EDM machining. The pulse on time, pulse off time and the applied current were the parameters used to study the material removal rate in EDM process. EDM drilling operations were conducted on an ELEKTRA PLUS spark erosion electrical discharge machine. 10 mm diameter brass tool was chosen to drill the MMC specimens. A mathematical model was computed to show a relationship of EDM machining process variables such as applied current, pulse on time and pulse off time on the MRR. The ANOVA (analysis of variance) method was performed to analyze the various input data on the output responses.

Numerical Study of the Toughness of Complex Metal Matrix Composite Topologies

Fracture toughness tests (compact tension) of a dual material composed of a structured Metal Matrix Composite (MMC) (martensitic steel and titanium carbides, named MS-TiC) surrounded by martensitic steel (MS) are simulated with a Discrete Elements Model (DEM) developed with the GranOO Workbench. The MMC structures are micro-lattices such as gyroid, octet-truss and Face and Body-Centered Cubic with Z-truss (FBCCZ). The volume fraction of these MMC inserts and their cell size are fixed, the influence of the cell orientation is studied. The aim of the study is to determine the configuration of topology (shape and cell orientation) which absorbs the most energy and is the most crack resistant. From experimental tests, the Young’s moduli and the failure stresses of the MMC material and the metal are estimated, and thanks to beam network discretization, a local stiffness and a failure criterion are evaluated to finally obtain a crack propagation path. To verify the suitability of the DEM model, a Compact Tension (CT) experimental test on MMC specimens is performed and a stress intensity factor is computed. A good agreement with an error less than 10% is obtained between experimental and simulated KIc with values respectively equal to 35 and 37 MPam. From DEM simulations based on the CT tests, the FBCCZ cell absorbs the most energy at the crack propagation compared to other structures and the steel. The crack propagation length depends on the shape of the topology. The originality of the study lies in the modeling, with granular properties using DEM, of the mechanical and elastic fracture behavior of these topological structures classically solved by Finite Elements Method (FEM): the microscopic constitutive relations have been validated macroscopically by experimental tests on homogeneous MMC materials.

Experimental investigation of aluminium hybrid metal matrix composites processed through squeeze casting process

In this experimental investigation, aluminium hybrid metal matrix composites (HMMCs) is fabricated through stir cum squeeze casting process. Zirconium Di-oxide (ZrO2) and graphite (C) is used as reinforcement. ZrO2 ceramic particles are used to increase the tensile strength of aluminium. Whereas C improves heat transfer properties that increases reliability of the product. Aluminium HMMCs used in this investigation with the following weight proportions − 100% AA6063; 95% AA6063, 3% C, 2% ZrO2; 91% AA6063, 3% C, 4% ZrO2; 86% AA6063, 3% C, 6% ZrO2 were fabricated using squeeze casting process. Microstructural study and mechanical behavior are characterized for different percentage of reinforcement on the squeeze cast metal matrix composite specimen fabricated as per ASTM standard. Microstructural study reveals the uniform and fine grain distribution of ZrO2 and C particles in the AA6063 HMMCs which in turn increases the tensile strength and hardness.

Parameter optimization and characterization of environmental friendly aluminium hybrid metal matrix composites

The present experimental investigation was carried out to fabricate environmental friendly hybrid aluminium metal matrix composites with three reinforcements in minimal amount through electromagnetic stir casting: an uncommon fabrication technique. Al 7075-T6 alloy was infused with three reinforcements; eggshell particles (wt% 0.5, 1 and 1.5, particle size ∼60 μm), SiC particles (wt% 1, 1.5 and 2, particle size ∼65 μm) and Al2O3 particles (wt% 1.5, 2 and 2.5, particle size ∼90 μm) with variable mechanical stirring time (2, 4 and 6 min). Composite fabrication experiments were run in accordance with Taguchi’s orthogonal array L9 and analysis of variance (ANOVA) was conducted to optimize process parameters and to observe their influence on quality characteristics. Developed composites were characterized for various physical and mechanical properties such as density, porosity, residual stress, micro hardness and tensile strength. Investigation outcomes show that synthesized hybrid composite specimen S8 with a total reinforcement content of 4.5% only, demonstrated no significant change in density (only upto 2.2%) whereas the maximum reduction in percentage porosity was 75%. Additionally, maximum abatement in residual stress of hybrid composite specimen S8 was 76% as compared to their unreinforced counterpart specimen S0, there was a maximum enhancement of 83% in microhardness and 107% in tensile strength of fabricated hybrid aluminium metal matrix composite specimen S8 in comparison of as-cast Al 7075-T6 specimen S0. Disposal of eggshells is a serious threat to environment, thus more focus was put on recycling them and using them for development of environmental friendly and cost effective hybrid composites with enhanced properties for numerous engineering applications.

Taguchi Optimization of Wire EDM Parameters for Surface Roughness of Al 6061 Alloy Based Composite With Sic Reinforcement

The Al 6061 alloy based Al- SiC metal matrix composite is rated as one of the most commonly used Metal Matrix Composites (MMCs) today. The MMC specimens studied in this research work were fabricated with the stir casting process. This research work studies important parameters in the wire electric discharge machining of Al-SiC 6061 MMC. We employed Taguchi approach to study the machining parameters during the machining process and to minimize the surface roughness values of the surfaces obtained by Wire EDM (Wire Electric Discharge Machine) machining. We found out that out of the seven factors used in this study, gap voltage during the wire EDM machining is the most prominent factor which influences the obtained surface roughness values. Comparatively, a very low value of surface roughness (Rq) was obtained by us during confirmation test by us.

Effect of milling time on the compressive high strain rate behavior of Al-SiC Composite

Aluminum-Silicon carbide (Al-SiC) metal matrix composite (MMC) have gained importance as a new class of material capable of serving the future generation brake material requirements. The presented study deals with the compressive high strain rate behavior of Al-SiC composite comprising 15% SiC by weight. The MMC specimens were fabricated by powder metallurgy route. Three different ball milling times were selected for the study purpose after optimizing all other processing parameters. Incorporation of SiC invariably enhanced the hardness, quasi-static and dynamic compressive strength of Al-SiC composite. Hardness was noted to enhance as a function of increasing ball milling time. However, the quasi-static and dynamic compression properties were recorded highest for the ball milling time of 240 minutes. The study confirms that minor addition of a suitable reinforcing material can significantly improve the properties of an MMC. Also, increasing the ball mill time may not necessarily enhance all the material properties.

Numerical analysis of the influence of the damping rings' thickness on interrupted dynamic tension results using SiC-reinforced ZC71 magnesium alloy specimens

Abstract. This article discusses the influence of the thickness of the damping rings used for interrupting a dynamic tension experiments on the results of a modified split Hopkinson tension bar (SHTB). In this paper a device enclosed in an external fixture used for interrupting a dynamic tension experiment in a SHTB is studied. The novelty of this manuscript with respect to previous studies lies in the fact that the dynamic tension experiment in a SHTB is interrupted in order to study the mechanical behavior of the material at high strain rates. The role played by such device is to interrupt the experiment at different levels of plastic deformation, particularly when the specimen is about to reach its failure strength. Finite-element (FE) simulations of high-strain-rate tension experiments are accomplished on a particle-reinforced metal matrix composite specimen (namely SiC-reinforced ZC71 magnesium alloy) when varying the thickness of the damping rings. Interrupting the test before the specimen breaks offers the possibility of being able to study in a more detailed way the deformation process of such material at high strain rates. Therefore, this work focuses on the study of the behaviour of materials undergoing high strain rates, developing a tool which allows materials to withstand different levels of strain rates in a controlled manner and providing guidance for future studies. In view of this research, it can be concluded that the thickness of the damping rings is a factor that can resolutely influence the interrupted dynamic tension experiment results avoiding the specimen's failure by optimally buffering the experiment using 0.8 mm thick lead damping rings.

Friction stir welding of hybrid AA 6061-ZrO2-C composites FSW process optimization using desirability approach

In the present work, friction stir welding (FSW) was employed to fabricate components made of metal matrix composites (MMC) by incorporating aluminium alloy, Zirconium Di-oxide (ZrO2) and Graphite (C) reinforcement particles into the aluminium AA6061 matrix. The weight percentage of MMC composition is 92% AA6061, 6% ZrO2, and 2% C. The stir cast MMC specimens were welded at the different FSW condition by changing the process parameters tool rotational speed, welding speed, and axial load. The desirability approach was used to optimize the FSW process parameters for simultaneous improvement of tensile strength and hardness of welded composites. From the investigation, it was found that the 190 MPa tensile strength and 50 HRB hardness with respective welding process parameters 852.82 rpm tool rotational speed,48.3 mm min−1 welding speed and 5.11 kN axial load.

Characterization of dry sliding wear mechanisms of AA5083/B4C metal matrix composite

Aluminium alloy is known to be a soft material with inadequate hardness, poor wear resistance and good castability; in order to improve its wear resistance, numerous researches have been conducted. This paper deals with the wear mechanisms of aluminium alloy (AA5083) composites reinforced with boron carbide (B4C) particles having 300 mesh size. The fabrication of aluminium metal matrix composite specimen by varying boron carbide in 5%, 10%, 15% and 20% of the weight of aluminium alloy was produced (composite-A, composite-B, composite-C and composite-D, respectively) by the stir-casting technique. The wear mechanisms of the developed metal matrix composites were studied at various parameters such as sliding distance (1000 m, 2000 m and 3000 m), load (30 N, 40 N and 50 N) and sliding velocity (1 m/s, 2 m/s and 3 m/s). The wear mechanisms of the prepared specimen (composites-A, B, C and D) were compared with each other under the same experimental condition on the pin-on-disc wear machine. The major findings in this paper are: the better wear resistance property of the developed metal matrix composites than that of the alloy used as matrix, the wear of composite has been linear and effortless prediction of the wear characteristics by the researchers.

Characterization & evaluation of Al7075 MMCs reinforced with ceramic particulates and influence of age hardening on their tensile behavior

Aluminium has a massive demand in the areas of automobile, aerospace and diverse engineering applications in order to furnish the requirement in those fields. But this technological evolution needs something more than aluminium. Materialogists are struggling hard to find out a material which owns sound mechanical and thermal properties and also superior than aluminium in each extent. Metal matrix composite (MMC) is a solution. Generally, metal matrix composites contain a low density material, i.e. aluminium or magnesium, reinforced with fibers or particulate of a ceramic material, i.e. silicon carbide or graphite. They show greater specific strength, high stiffness, elevated operating temperature, and superior wear resistance, along with the possibility to customize these properties for a specific use. In this study, Al 7075 is taken as a base matrix material, whereas ceramic materials like SiC, Al2O3, B4C and TiB2 are used as reinforcements. There are different methods available for fabricating metal matrix composite materials and in this work, stir casting technique, which is a liquid state process, is used. Four different MMC specimens were produced with 15 % SiC, 15 % Al2O3, 15 % B4C and 15 % TiB2. Mechanical properties i.e. tensile strength, hardness, and impact strength were studied for the prepared specimens. The results were charted and presented graphically to describe these materials characteristics.

High temperature characteristics of Al2024/SiC metal matrix composite fabricated by friction stir processing

In the present study, friction stir processing (FSP) is used for the synthesis of an aluminum metal matrix composite (MMC) reinforced by SiC particles. MMC specimens with reinforced microstructures exhibited significant improvement in hardness (near 50%). Isothermal uniaxial tensile tests were employed for the as-received, friction stir processed and composite microstructures at ambient and high temperatures under strain rates ranging from 10−2 to 10−4 s−1 to investigate the effect of deformation rate on the mechanical behavior. At ambient temperature, notable improvement of the yield strength was observed reaching about 240% of the as-received samples while the ductility was reduced near to 4%. Elevated temperature flow curves were perceptibly sensitive to strain rate, especially for FSPed and MMC samples. Fracture surface observations hinted at the distribution of second phase particles along with possible damage mechanisms.

Mechanical behavior enhancement of AZ31/WS2 and AZ61/WS2 magnesium metal matrix nanocomposites

This study conducted tensile and hardness tests to compare the mechanical properties of Mg alloys and metal matrix composites with and without WS2 or multi-walled carbon nanotubes. We also examined the microscopic structures to investigate their failure characteristics. Our results indicate that AZ61 presented the best mechanical properties following the addition of WS2 and solution heat treatment, and increasing the content of WS2 improved the mechanical properties. This performance of this combination even outperformed that of metal matrix composites containing multi-walled carbon nanotubes. This study developed an image processing method, in which X-ray images of the metal matrix composite specimens undergo filtering, binarization, edge enhancement, and morphological calculations to determine the area of internal defects in Mg metal matrix composites. The results indicated reduced percentage of internal defect area values in AZ31-T4 and AZ61-T4 following the addition of 0.2% WS2 inorganic nanotube (INT). X-ray diffraction results revealed that the solution heat treatment process causes the WS2 to dissolve into the Mg base, thereby shifting the peak to the right. This improves solid solution strengthening and enhances the mechanical properties. Further observation of the microscopic structures indicated that the AZ61-T4 possesses finer grains than does the AZ31-T4, which is consistent with the existing literature.

Reciprocating wear behavior of 7075Al/SiC in comparison with 6061Al/Al2O3 composites

In the present study, the reciprocating wear behavior of 7075Al/SiC composites and 6061Al/Al2O3 composites that are prepared through liquid metallurgy route is analyzed to find out the effects of weight percentage of reinforcement and load at the fixed number of strokes on a reciprocating wear testing machine. The Metal Matrix Composite (MMC) pins are prepared with different weight percentages (10, 15 and 20%) of SiC and Al2O3 particles with size of 36μm. Hardness of these composites increases with increase in wt.% of reinforcement. However, the impact strength decreases with increase in reinforcement content. The experimental result shows that the volume loss of MMC specimens is less than that of the matrix alloy. However, the volume loss is greater in 6061Al/Al2O3 composites when compared to 7075Al/SiC composites. The temperature rise near the contact surface of the MMC specimens increases with increase in wt.% of reinforcement and applied load. The coefficient of friction decreases with increase in load in both cases.

Effect of the amount of SiC, number of strokes, and applied load on the reciprocating wear behavior of Al-SiC composites

Abstract The wear behavior of Al/SiC composites prepared by stir casting technique is investigated to find out the effects of the weight percentage of SiC, load, and the number of strokes on a shaper machine. Metal matrix composite (MMC) pins are prepared with different weight percentages of SiC (10%, 15%, and 20%). The tests are carried out with different load conditions (25, 50 and 75 N) and different number of strokes (420,780 and 1605 strokes). Wear surfaces of tested samples are examined in scanning electron microscope (SEM). Hardness and impact tests are also carried out on the MMC samples. The experimental results show that the hardness of composites increases with an increase in SiC particle, and the impact strength decreases with increase in SiC content. The volume loss of MMC specimens are less than that of the matrix alloy. Moreover, the temperature rise near the contact surface of the MMC specimens increases with increase in wt% of SiC, load, and number of strokes. The coefficient of friction decreases with increase in load and the number of strokes.